Spot on, MD.
The προς seems to me, as a Trinitarian, to argue against modalism, not against the Trinity.
That is a valid point, but I don't think modalism was an issue even in the late first century, when "John" wrote. No one believed that God the Father appeared as Jesus or that God the Father became flesh. The problem with "John' is the fact that it is heavily interpolated and that apparently more than one auhtor contributed his beliefs to the book.
I generally construe the confessions of IHS as Κυριος to be confessions that He is THE God.
Κυριος is simply a title of superiority or rank, not necessarily or exclusively a divine title. It is equivalent to the English "Sir." The Apostles never prayed to Jesus (earthly or risen), but only to God, the Father. There was never any confusion in that respect who was God and who was their lord (κυριος)
It is my understanding that, while Κυριος is as you say, it is also the word used in the LXX for the Holy Name.